Integrator mechanism for line sectionalizers



P 22, 1953 J; M. WALLACE ET AL 2,653,201

INTEGRATOR-MECHANISM FOR LINE-SECTIONALIZERS Filed July 21, 1950 WITNESSES: INVENTORS James M. Wallace a d BAYndrew W. Edwards.

' ATTORNEY Patented Sept. 22, 1953 INTEGRATOR MECHANISM FOR LINE SECTIONALIZERS James M. Wallace and W. Edwards, East McKeesport, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a

corporation of Pennsylvania Application July 21, 1950, Serial No. 175,214

17 Claims.

1 Our present invention relates to integratormechanisms for line-sectionalizers. More particularly. it relates to a novel type of integratormechanism which has no time-delayed parts, thereby avoiding the cost and the unreliable operation which have been involved in the various dashpots, mechanical escapements, and other fault-current appears whenever the reolosercontacts are closed. At the end of this predetermined number of counts, the reoloser automatically locks itself out, so that the line is not energized again.

The distribution-line or system is subdivided into a number of sections by one or more linesectionalizers, each of which responds to faultcurrents which occur in its own section. Each sectionalizer counts a predetermined number of rapidly recurring overcurrent-conditions, this sectionalizer-count being less than the reolosercount, and finally the sectionalizer opens its linecontact during a no-current period of the recloser, thus removing or deenergizing the section where a permanent or non-self clearing fault exists, and permitting the rest of the distributionsystem to continue in service.

The counting mechanisms which. are used in the sectionalizers and in the reoloser are called integrators. It is necessary that these integrators shall be automatically self-resetting, and this resetting-operation has heretofore been usually accomplished with the aid of timing devices.

Our present invention relates to integrators for the line-sectionalizers. Since these sectionalizers do not opentheir line-contacts when there is any line-current flowing, they may be made relatively inexpensively, being nothing more than an integrator and a disconnect-switch. It is essential, therefore, that the integrator shall be as simple and as inexpensive as possible.

In our present integrator, we use an electromagnet having an armature which moves back and forth, from its unattracted position to the position to which it is attracted when the integrator-coil is energized with an adequate overcurrent. The movements of the armature ,toward its attracted position are used to advance a counter-rod in a step-by-step fashion, and each time the armature moves back, after advancing the counter-rod, a holding-detent engages the rod andholds it in an advanced position. As long as overcurrent-conditions continue to appear, in the integrator-coil, followed by no-current periods, the above-described armature-movement continues to notch the counter-rod still further forward. According to our invention, a normal current-condition, as distinguished from an overcurrent-condition, is used to effect the release of the holding-detent, and permit the instant resetting of the counterrod, regardless of the number of notches through which it had been advanced.

Our invention provides a novel means whereby a single armature, which is biased towards an intermediate position, will move in one direction in response to normal currents, and in the other direction in response to overcurrents, with mechanism arranged to notch the counter-rod forward in response to the overcurrent-movements, and to trip out the holding-detent in response to the normal-current condition.

A further feature of our invention involves a special latching-means whereby the final response of the integrator is obtained during a nocurrent period, and not during the last overcurrent-period which is permitted by the number of counts which are responded to by the integra- With the foregoing and other objects in view, our invention consists in the apparatus, systems, mechanisms, parts, and methods of design and operation, hereinafter describedand claimed, and illustrated in the accompanying drawing, the single figure of which is a diagrammatic vertical sectional view of an integrator-mechanism illustrative of our invention.

The description and explanation of our invention may conveniently be divided into three parts. First, there is an electromagnet-part I, which is shown at the top of the figure, and which has a movable armature 2 which serves as a threesposition movable operating-member which is-biasecl toward its intermediate position, and which moves to one extreme position in response to currentvalues within a normal current-range, and which moves to its other extreme position in response to currents in excess of said normal range. Next, on the drawing, comes the counting mechanism 3, which counts the number of discrete overcurrent-movements of the armature 2, which occur before there is any period during which normal current flows. And finally, at the bottom of the figure, there is the special latch-mechanism 4 which stores up information that the desired number of overcurrent operations have been obtained, until there is no longer an overcurrent, after which a response to the integrator-mechanism is permitted.

The electromagnet I is a special current-responsive mechanism comprising a coil 5 which is a part of a stationary frame including an upper pole-piece 6 and a lower pole-piece I. These two pole-pieces are Joined by a tube 8 of insulation or other non-magnetizable material. This electro-- magnet frame may be supported in any way, as by means of a support-bracket 9. In the illustrated embodiment of our invention, the insulating tube It stands in a substantially vertical position, and for convenience it will be "described as if itwere in that position, although it is obvious that we are not limited to a vertical position.

Inside of the insulating tube 8, at the upper end thereof, we provide a movable upper pole-piece I I, which is slidably movable within the tube 2, and which ispressed up against thetop of the tube by means of a compression-spring II' which is shown as abutting against an insulating or nonmagnetizable sleeve I2 which is secured within the tube 8.

The armature 2 is axially movable inside of the sleeve I2. Secured to the bottom of this armature 2 is an axially depending magnetizable armature-rod I3, which extends freely through an axial hole I4 through the lower pole-piece I, and on down to the counting-mechanism 2 which will be subsequently described. An intermediate portion of the armature-rod I3 is provided with a washer or shoulder I5, which is held between two compression-springs I8 and II, which bias the armature to an intermediate position which is below the normal spring-held positionof the movable upper pole-piece I I, and above the lower pole-piece I, as shown in the drawing. That portion of the armature-rod I3 which extends up between the lower pole-piece I and the armature 2 is of such restricted cross-sectional area that it is saturated during overcurrent conditions, but not during normal-current conditions.

As a result of this electromagnet-construction,

the armature-rod I3, in its unsaturated condition, will carry the magnetic ilux from the lower pole-piece I to the armature 2, during a normal range of current-values, thus permitting the top of the armature 2 to be attracted upwardly to the bottom of the movable upper pole-piece II, during these normal-current conditions. The spring II, which holds up the movable upper pole-piece II in its normal uppermost position, is strong enough to resist the pull of the armature 2 during these normal-current conditions, so that the armature moves upwardly to meet the upper pole-piece during said conditions.

When a predetermined overcurrent-condition is obtained, the design is such that the magnetizable armature-rod I3 saturates, thus allowing flux to flow in the air gap between the top of the lower pole-piece I and the bottom of the armature 2. The armature 2 is thus attracted in both directions, both downwardly toward the lower pole-piece I, andupwardly toward the movable upper pole-piece II. The strong magnetic flux due to the overcurrent-value is enough to overcome the bias of the spring I I, so that the returns to its predetermined intermediate posithan during zero currents or currents below the normal range of load-currents for which the apparatus is designed.

The counting-mechanism I and the latchinsmechanism 4 of the integrator are housed In a downwardly depending tube II, which is secured to the bottom of the lower pole-piece I, so that the two tubes 2 and I. serve as coaxial extensions of each other.

The counting-mechanism 2 include an axially movable operating-member 20 which is carried by the lower end of the armature-rod I2, and an upwardly biased axially disposed counter-bar 2|. As shown, the lower end of the counter-bar is biased upwardly, toward its resetting position, by means of a compression-spring 2| which presses up 021: a shoulder 2|" carried by the counterbar The operating-member 2! slides freely up and down within the lower tube II, in accordance with the movements of the armature 2. The lower end of this operating-member 20 is provided with 9. lug 22 to which is pivoted a tiltable pawl or ratchet 22, which serves as a one-way drive-mechanism for causing the counter-bar 2| to take one step or a step-by-step downward advance-movement away from the armature-position, each time the armature moves downwardly to the fixed lower poleiece 1 during an overcurrent-condition in the coil 2. The pawl or ratchet 22 is yieldably canted, as by means of a spring 23', so that its lower edge engages one of a series of notches 24 on the counter-bar 2 I, each time the armature 2 moves downwardly to its overcurrent position.

As shown in the drawing. the top of the operating-member 20 is provided, on one side, with a slot 25 which is wide enough to receive a lug 26 which extends inwardly from the side wall of the lower tube It. This lug 26 -is used to pivotally support a holding detent 21, which is biased toward a canted position by means of a suitable spring 21'. This holding-detent thus engages any one of a second series of notches 22 on the counter-bar 2|.

The result of the foregoing construction is that, each time the armature 2 moves downwardly to its overcurrent position, the advancingpawl 23 notches the counter- -bar 2| downwardly one step in its step-by-step advancement. Whenever the armature returns upwardly to its intermediate unattracted position, the counter-advancing pawl 23 moves up, readily for engagement with the next notch 24 in thecounter-bar 2|, while the holding-detent 21 catches behind one of the holding-notches 28, and causes the counter-bar 2| to retain at least a portion of its downwardly notched advance. This stepby-step downward advancement of the counterbar 2| continues every time there is an overcurrent-condition, followed by a zero-current condition, or a current-strength less than the minimum value necessary to move the armature to the upper limit of its travel.

If the fault which caused the overcurrentcondition are itself before the counter-bar 2| completes its predetermined number of advancesteps, then, of course, there will be no, further notching-advance of the counter-bar 2|. Ordinarily. when the fault disappears, there will be a normal current-flow which is sufilcient to lift the armature 2 to its uppermost position. For example, the current which is required to lift the armature 2 may bein the range between 20% and 100% of the normal full-load current in the line in which the integrator-mechanism is connected. or any other suitable. normal current-range may be chosen.

When such a normal current-value is established in the coil I, the armature 2 rises to its topmost position, drawing up the operatingmember 20 with it. When this operating-member 20 moves upwardly to itstopmost position, the bottom of its slot 25 engages an edge of the holding-detent 21, and straightens it into a horizontal position in which it releases its engagement with one of the holding-notches 28, and permits the counterbar 2| to instantly reset itself, by moving upwardly to its initial unadvanced position, under the impetus of its biasing-spring 2|. It will be noted that this resetting-operation is instantaneous, and independent of the number of advance-steps which have been made by the counter-bar 2|, being dependent only upon the occurrence of a current-value in the normal range.

If, after the fault has cleared itself, and before the counter-bar 2| has completed its prescribed number or count of advance-steps, the fault-free load on the line should be so small that the load-current is not large enough to pick up the armature 2 to its topmost position, then the integrator or counter-mechanism will remain in its partially advanced position until normal current does appear; or if a fault should occur before this normal current appears, then the counting-mechanism will resume its count from the point at which it previously left 011.

It will be noted that the counting-operation of the counting-mechanism is not dependent upon the rapidity of the occurrence of successive overcurrent conditions, but only upon the occurrence of successive overcurrent-conditions, separated by no-current conditions, regardless of the time-intervals between successive overcurrent-conditions, so long as no normal currentvalues appear in the meantime.

When the counter-bar 2| has been downwardly advanced through its predetermined number of advance-steps, some means must be provided for effecting a desired integrator-response, such as opening the line-contact (not shown) of a line-sectionalizer.

It will be noted, from the foregoing description, that the particular counting-device 3 which is illustrated uses an operating member 2|! which is disposed on the overcurrent side of the travellimits of the armature 2, so that the operatingmember 20 is advanced during the movement of the armature toward its overcurrent position, as distinguished, for example, from advan cing when the armature returns from its overcurrent position. Since this is the case, it is usually necessary or desirable to provide some arrangement for absorbing the information that the counter-bar 2| has reached the limit of its predestined advancing movement, and to retain this information until the last overcurrentcondition is interrupted, usually by recloser (not shown). For this reason, a special latch-mechaaosaaoi 6. nism is usually desirable, as shown at 4 at the bottom of the drawing.

In the illustrated latch-mechanism 4, the bottom of the integrator is equipped with an axially disposed response-rod 30, which extends up a little way into the bottom of the tube I8, and which is biased upwardly toward a responding position, as by means of a spring 30'. This response-rod 30 is provided with a shoulder 3|, above which is disposed a suitable latch 32 which is carried by the tubular housing It at a point The particular type of latch 32 which is shown in the drawing is in the form of a, thin axially disposed tube 32, the top end of which is secured in an annular plug 33 which is secured within the housing-tube It. The lower end of the latchtube 32 is slit into a plurality of fingers, which are bent inwardly to form a tulip-type end 34. The inner diameter of the latch-tube 32 is sufllciently large to permit the response-rod shoulder 3| to move upwardly into said latch-tube, when the tulip-fingers 34 are expanded. A slidable sleeve or inverted cup-member 35 is disposed inside of the latch-tube 32, in the path of the downwardly advancing counter-bar 2|, so that, when the counter-bar makes its final downward advance-movement, it pushes the inverted cupmember 35 downwardly, causing it to expand the tulip-fingers 34, thus releasing the latch 32 from its engagement with the response-rod shoulder 3|.

It will be observed that, at the same time when the last advance-movement of the counter-bar 2| releases the latch 32, the counter-bar 2| also abuts down against the inverted cup-member 35, which in turn abuts down against the responserod shoulder 3|, thus mechanically holding said response-rod 30 against substantial movement in its upward responding-direction, as 10Ilg as the counter-bar 2| is in its fully advanced downward-position.

The last downward advance of the counterbar 2|, when the armature 2 moves down to its overcurrent-position for the last time, is somewhat lower than the counter-bar position in which it will be retained by the last holdingnotch 28, under the action of the holding-detent 21, when the armature 2 moves back upwardly again. In other words, when the armature 2 moves back upwardly away from its lowermost overcurrent-position for ,the last time, the counter-bar 2| is withdrawn back for a fraction of its last advance-step, before said counter-bar reaches its last detent-held advanced-position. This slight upward withdrawal of the counterbar 2| is requisite only upon the cessation of the last overcurrent-condition, and it permits the response-rod 30 to make a substantial or adequate upward-movement, in its responding direction, under the impetus of its spring 30. This upward movement of the response-rod 30 constitutes the final response-operation of the integrator-mechanism. This response-operation may be used to control any desired mechanism, for instance a latch-member 36, which is to be controlled by the integrator-mechanism.

While we have illustrated our invention in only a single illustrative form of embodiment, we wish it to be understood that our invention is not shown, and we desire that our appended claimsmay be accorded the broadest construction consistent with their language.

We claim as our invention:

1. An integrator-mechanism comprising: a three-position movable operating-member, biasing means biasing said operating-member toward its intermediate position; current-responsive means for moving said movable operating-member to one extreme position in response to current-values within a normal current-range, and for moving saidmovable member to its other extreme position in response to currents in excess said normal range; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism operatively connecting the operating-member and the counter-member for imparting one step or a step-bystep advance to said counter-member in response to movement of said operating-member to one of its extreme positions; a holding-detent for engaging and holding said counter-member in advanced positions; and means for releasing said holding-detent in response to movement of said operating-member to the other its extreme positions.

2. The invention as defined in claim 1, characterized by said current-responsive means comprising: a magnetizing coil having two pole terial; a magnetizing coil for causing a magnetic fiux to flow axially in a portion or said tubular member; a centrally perrorated fixed pole-piece in said tubular member ,at one end of the region through which axial fiux flows; an axially movable poie-piece in saidtubular member at the other end or the region through which axial fiux flows; an armature within said tubular member. said armature being axially movable between said pole-pieces; means for biasing said armature toward an intermediate position spaced between said two pole-pieces; biasing-means for holding said movable pole-piece in an undisplaced position away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal current-values in the coil. but not strong enough to resist overcurrent-values; and a saturable armature-rod secured to said armature and passing slidably through the central perforation in the fixed polepiece. whereby the attraction of said fixed polei piece for the armature is strongly reduced by the pieces; a movable armature which is biased to-..

ward an intermediate position spaced between said two pole pieces; a first one of said pole pieces being movable toward said armature and having biasing-means for holding it away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal current-values in the coil, but not strong enough to resist overcurrent-values, and means providing a saturable flux-path joining said armature to the second pole piece while permitting the armature to move in either direction, whereby the attraction 01 said second pole piece for the armature is held at a reduced value by said saturablefiux-path as long as said path 1 remains unsaturated, and is increased upon said path becoming saturated on overcurrent-values.

3. The invention as defined in claim 1, characterized by said current-responsive means comprising: a non-magnetic tubular member; a magnetizing coil for causing a magnetic fiux to fiow axially in a portion of said tubular member; a fixed pole-piece in said tubular member at one end of the region through which axial fiux flows; an axially movable pole-piece in said tubular member at the other end of the region through which axial flux flows; an armature within said tubular member, said armature being axially movable between said pole-pieces; means for biasing said armature toward an intermediate position spaced between saidtwo pole-pieces; biasing-means for holding said movable polepiece in an undisplaced position away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal current-values in the coil, but

not strong enough to resist overcurrent-values; and a saturable means whereby the attraction of said fixed pole-piece for the armature is strongly reduced as long as said saturable means remains unsaturated, said saturable means becoming saturated on overcurrent-values.

4. The invention as defined in claim 1, characterized by said current-responsive means comprising: a tubular member or non-magnetic maflux-path which is provided by said armaturerod as long as said path remains unsaturated.

said path becoming saturated on overcurrentvalues.

5. A current-responsive mechanism comprising: a magnetizing coil having two pole pieces; a movable armature means biasing said armature toward an intermediate position spaced between said two pole pieces; a first one of said pole pieces being movable toward said armature and having biasing-means for holding it away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal current-values in the coil, but not strong enough to resist overcurrent-values, and means including a saturable armature extension movable relative to the second pole piece for providing a saturable flux-path Joining said armature to the second pole piece while permitting the armature to move in either direction, whereby the attraction of said second pole piece for the armature is strongly reduced by said saturable flux-path as long as said path remains unsaturated, said path becoming saturated on overcurrent-value.

6. A current-responsive mechanism comprising: a non-magnetic tubular member; a magnetizing coil positioned relative to the tubular member for causing a magnetic flux to flow axially in a portion of said tubular member; a fixed pole-piece in said tubular member at one end 01' the region through which axial'fiux flows; an-

axially movable pole-piece in said tubular member at the other end of the region through which axial flux flows; an armature within said tubular member, said armature being axially movable between said pole-pieces; means for biasing said armature toward an intermediate position spaced between said two-pieces; biasing-means for holding said movable pole-piece in an undisplaced position away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal currentvalues in the coil. but not strong enough to resist overcurrent-values; and a saturable means magnetically coupling the armature to the fixed polepiece whereby the attraction of said fixed polepiece for the armature is strongly reduced as long as said saturable means remains unsaturated, said saturable means becoming saturated an overcurrent-values so as to permit the attraction of the fixed pole-piece tor the armature to increase.

'7. An integrator-mechanism comprising: a tubular member substantially or non-magnetic material; a magnetizing coil disposed relative to said tubular member for causing a'magnetic flux to flow axially in a portion oi said tubular member; a fixed pole-piece in said tubularmember at one end of the region through which axial flux'fiows; an axially movable pole-piece in said'tubular member at the other end of the region through which axial'flux fiows; an armature within said tubular member, said armature being axially movable between said pole-pieces; means for biasing said armature toward an intermediate position spaced between said two pole-pieces; biasing-means for holding said movable polepiece in an undisplaced position away from the armature with a force which is greater than that of the magnetic attraction caused by normal current-values in the coil, but not strong enough to resist overcurrent-values; a saturable means magnetically connecting the fixed pole piece and armature whereby the attraction of said fixed pole-piece for the armature is strongly reduced as long as said saturable means remains unsaturated, said saturable means becoming saturated on overcurrent-values; anoperating-member responsive to the movements of said armature within said tubular member; an axially movable counter-bar which is disposed axially within said tubular member; means for biasing said counterbar toward a limit of its movement; a one-way drive-mechanism operatively connecting the operating member and counter-bar for causing said counter-bar to take one step of a step-bystep advance-movement each time said armature moves in one direction; a holding-detent carried by said tubular member for engaging and holding said counter-bar in advanced positions; and means for causing said operating-member to release said holding-detent each time the armature moves in the other direction.

8. The invention as defined in claim 7, in combination with a response-member which is biased in an axial direction; a latch which is carried by the tubular member, said latch being normally in such position that it engages and holds said response-member against movement in its biased direction; and means whereby the counter-rod, at the termination of its predetermined step-bystep advance, pushes back said latch and at the same time holds said response-member against gap between saidfixed pole-piece and the armamagnetic flux across said air gap increasing upon,

said path becoming saturated on overcurrentvalues.

10. An integrator-mechanism comprising: a tubular member having at least a portion thereof of a non-magnetic material; a magnetizing coil positioned relative to the tubular member for causing a magnetic flux to flow axially. in a portlon of said tubular member; a. centrally peri'orated fixed pole-piece in said tubular member at one end of the region through which axial flux flows an axially movable pole-piece in said tubular member at the other end of the region through which axial flux flows; an armature within said tubular member, said armature being axially movable between said pole-pieces; rmeans tor biasing said armature toward an intermediate position spaced between said two polepieces; biasing-means for holding said movable polep1ece in an undisplaced position away from the armature with a force which is strong enough to withstand the magnetic attraction caused by normal current-values in the coil, but not strong enough to resist overcurrent-values; a saturable armature-rod secured to said armature and passing slidably through the central perforation in the fixed pole-piece, whereby the attraction of said fixed pole-piece for the armature is strongly reduced by the flux-path which is provided by substantial movement as long as said counterrod is in its advanced position.

9. A current-responsive mechanism comprising: a tubular member at least a portion of which is of non-magnetic material; a magnetizing coil positioned for causing a. magnetic fiux to flow axially in a portion of said tubular member; a centrally perforated fixed pole-piece in said tubular member at one end of the region through which axial flux flows; an axially movable polepiece in said tubular member at the other end of the region through which axial flux flows; an armature within said tubular member, said armature being axially movable between said polepieces; means for biasing said armature toward an intermediate position in which it is spaced from each of said two pole-pieces by an air gap; biasing-means for holding said movable polepiece in an undisplaced position away from the armature with a force which is strong enough to withstand the magnetic attraction which is caused by normal current-values in the coil, but not strong enough to resist overcurrent,-values; and a saturable armature-rod secured to said armature and passing slidably through the-central perforation in the fixed pole-piece, whereby the attraction of magnetic flux across the air said armature-rod as long as said path remains unsaturated, said path becoming saturated on overcurrent-values; an operating-membercarried by the portion oi. said armature-rod which projects through the fixed pole-piece; an axially movable counter-bar which is disposed axially within said tubular member; means for biasing said counter-bar toward the limit of its movement which is closest to said armature; a oneway drive-mechanism for operatively connecting said counter-bar and armature and causing said counter-bar to take one step of a step-by-step advance-movement away from said armature each time said armature moves to the fixed polepiece; a holding-detent carried by said tubular member for holding said counter-bar in advanced positions; and means for causing said operatingmember to release said holding-detent each time the armature moves to the undisplaced movable pole-piece.

11. The invention as defined in claim 10, in combination with a response-member which is biased in an axial direction toward the end of said counter-rod; a latch which is carried by the tubular member at a point between said responser member and said counter-rod, said latch being normally in such position that it engages and holds said response-member against movement in its biased direction; and means whereby the counter-rod, at the termination of its predetermined step-by-step advance, pushes back said latch and at the same time holds said responsemember against substantial movement as long as said counter-rod is in its advanced position; the last advance of said counter-rod being beyond the last position in which said counter-rod is held by said holding-detent, whereby, upon cessation of said overcurrent, the counterrod is withdrawn back to said last detent-held position and permit: said response-member to follow said counter-rod past said latch.

12. An integrator-mechanism comprising: a

tubular member; a magnetizing coil for causing a magnetic flux to now axially in a portion of said tubular member; an armature within said tubular member, said armature being movable between a retracted position and an advanced position to which said armature is drawn by an overcurrenteenergization of said coil; means for biasing said armature toward the retracting direction: an axially movable counter-bar which is dis osed axially within said tubular member; means for biasing said counter-bar toward an inoperative position: a one-way drivemechanism connecting the armature and counter-bar for impartin one step of a step-bv-step advance to said counter-bar each time said armature advances to its overcnrrentositions: a holdin -det nt carried by said tubular member for holding said counter-bar in advanced positions: a res onsemember which is biased in an axial direction toward the end of said counter-rod: a latch which is carried by the tubular member at a point bet-reen said response-member and said counterrod. said latch bein normally in such position that it en ages and holds said res onse-member against movement in its biased direction: and means whereby the counter-rod. at the termination of its predetermined stcn-by-step advance. pushes baclr said latch and at the same time holds said response-member against substantial movewent as long'as said counter-rod is in its ad- "rmced position: the last advance of said connterrod being beyond the last position in which sa d munter-rod is held by said holding-detent, whereby. upon cessation of said overcnrrent. the counter-rod is withdrawn back to said last detentheld osition and ermits said res onse-member to follow said co nter-rod past said latch.

13. An inte rator-mechanism com rising: an operat ng-member which moves between a retra cted position and an advanced position: a movable counter-member which is biased toward an ino eratre position; a one-way drive-mechanism effect vely connecting the operating-member and counter member for imparting one step 01' a step-by-step advance to said counter-member each t me said operatin -member moves to its advanced position: a holding-detent for holding said counter-member in advanced positions; a response-member which is biased toward the advancing end of said counter-member; a latch which is disposed at a point between said response-member and said counter-member, said latch being normally in such position that it holds said res onse-member against movement in its biased direction; and means whereby the counter-member, at the termination of its predetermined step-by-step advance, pushes back said latch and at the same time holds said response-member against substantial movement as lon as said counter-member is in its advanced position; the last advance of said counter-member being beyond the last position in which said counter-member is held by said holding-detent, whereby, when said operating-member moves back from its last advanced position, the countermember is withdrawn back to said last detentheld position and permits said response-member to follow said counter-member past said latch.

14. An integrator-mechanism comprising: an operating-member which moves between a retracted position and an advanced position; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism providing an operating connection between the operating-member and counter-member ior 12 imparting one step of a step-by-step advance to said counter-member each time said operatingmember moves to its advanced position: a holding-detent for holding said counter-member in advanced positions; a response-member which is biased toward a responding position; a latch for normally holding said response-member from responding; and means whereby the countermember,at the termination of its predetermined step-by-step advance, releases said latch and at the same time mechanically holds said responsemember against substantial movement in its responding direction as long as said countermember is in its iuliy advanced position; the last advance of said counter-member being beyond the last position in which said counter-member is held by said holding-detent. whereby, when the operating-member moves back from itslast advanced position, the counter-member is withdrawn back to said last detent-heid position and permits said response-member to make a substantial movement in its responding direction.

15. An integrator-mechanism comprising: an electrom n t device having a coil and an armature which is movable from a predetermined unattractedposition to a predetermined attracted position to which it is attracted by the magnetic flmr produced by a predetermined overcurrent in the coil: a movable couptor-member which is biased toward an inoperativ'e, position; a one-way drive-mechanism eiiectively connecting the armature and the counter-member for imparting one step of a step-bystep advance to said counter-member each time said armature moves to its overcurrent-position; a holding-detent for holding said counter-member in advanced positions; a response-member which is biased toward a responding position; a latch for normally holding said response-member from responding; and means whereby the counter-member, at the termination of its predetermined step-by-step advance, releases said latch and at the same time mechanically holds said response-member against substantial movement in its responding direction as long as said counter-member is in its fully advanced position; the last advance of said counter-member being beyond the last position in which said countermember is held by said holding-detent, whereby,

when the armature moves back from its overcurrent position for the last time, the countermember is withdrawn back to said last detentheld position and permits said response-member to make a substantial movement in its responding direction.

16. An integrator mechanismcomprising: an operating member having three operating positions, biasing means actuating said member to one of the positions, electromagnetic means for moving said operating member to another one of the positions in response to a current value within a normal current range and for moving said operating member to the other of the positions in response to a current in excess of said normal range, a movable counter-member normally disposed in a rest position, means operatively connecting the operating-member and the countermember for imparting a one way step-by-step advance of said counter-member in response to repeated movements of said operating-member to said other of the positions, and means operable in response to movement of the operatingmember to its other extreme position to eil'ect return of the counter-member to its rest position.

1'7. In an integrating-mechanism, a movable 13 armature, biasing means biasing the armature to an intermediate position, electromagnetic means including a magnetizing coii having a pair of pole pieces disposed on opposite sides of the armature for moving it to one extreme position in response to currents within a normal operating range and to its other extreme position in response to a current in excess of said normal range, a movable counter-member biased to an inoperative position, drive means operatively connecting the counter-member and the armature to effect a one way step-by-step advance of said counter-member in response to movement of said armature to one extreme position, and means operable in response to movement of the armature to its other extreme position to References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,227,341 Stratton May 22, 1917 1,354,881 Canfield Oct. 5, 1920 1,629,815 Aikman May 24, 1927 1,982,986 Garlington Dec. 4, 1934 2,334,339 Lemmon Nov. 16, 1943 2,387,732 Watkins Oct. 23, 1945 

